The roots of ginseng plants, including Panax ginseng (also called Panax schinseng), Panax pseudo-ginseng, Panax quinquefolium and Panax japonicum contain saponins and sapogenins and have long been used as crude drugs. The roots of these ginseng plants and a dried product are called "ginseng drug" or merely "ginseng". In many countries of Asia, people have said that the ginseng is a very valuable medicine which promotes health and enhances man's lease of life. Recently it has scientifically been confirmed that ginseng exhibits some sedative activity, stimulative activity and diuretic activity. It has been reported that ginseng, namely the crude drugs which are obtained from the ginseng plants, contain inter alia saponins, sapogenins, vitamin B group compound, and .beta.-sitosterol D-glucoside, as the active or medicinal ingredients but it has been elucidated that the main active ingredients of ginseng are saponins and sapogenins (see the specification of U.K. Pat. No. 1,348,324).
The root of ginseng plants has several branched small roots and a number of long, thin fibre-like roots and exhibits a unique and miscellaneous appearance and shape which are worthy of being appreciated or admired aesthetically. Besides, the raw root of the ginseng plants, that is the crude ginseng, is likely to be spoiled by bacterial and fungal infestation during storage and often is stored while being dipped in aqueous ethanol containing usually 40.about.80% water. This storage of ginseng in aqueous ethanol may be done in a transparent vessel made of, for example, glass cylinder containing a volume of aqueous ethanol for the purpose of aesthetic appreciation or admiration of the miscellaneous appearance or shape of the ginseng root.
In order to prevent the crude ginseng from spoiling, the crude ginseng is often dehydrated, affording dried ginseng. The dried ginseng is easy to be handled in the commercial route and may be dipped in aqueous ethanol to restore its original miscellaneous shape of the crude ginseng. When the dried ginseng is dipped in aqueous ethanol, the pharmacologically active ingredients of the ginseng can be extracted into the ethanol, and the ethanolic extract (the elixir) so obtained is useful as medicinal spirit beverage or liquor drug which maintains and promotes the health of men.
The dried ginsengs known heretofore include those which have been sun-dried and those which have been dried by hot air and sun-dried, and they are called Ginseng Radix alba or Ginseng Radix rubra. Ginseng Radix alba is the one obtained by peeling the outer skin off from the crude ginseng root (often called as Ginseng Radix) and then drying under sunlight, while Ginseng Radix rubra is produced by treating the crude Ginseng Radix as such with hot water or steam and then drying under sunlight or by hot air. Ginseng Radix is thus made from the root of ginseng plants belonging to the family Araliaceae, and the main part of this root consists of compact and rigid tissue cells, significantly different from those soft and flexible tissue cells of the usual cultivated vegetable carrot which belong to the family Umbelliferae. The outer skin of this ginseng root consists of phellem (cork-tissue) and collenchyma and its xylem has compact and rigid fibrous tissue, so that the aforementioned drying by sunlight or hot air applied to the ginseng root is usually not complete and substantially renders a high content of moisture to be remaining in the dried products of Panax Radix alba and rubra. This amount of residual water will tend to deteriorate the dried ginseng due to infestation with fungi and bacteria during the storage. Besides, the drying by sunlight or hoot air is likely to bring about shriveling and hardending of ginseng tissue in the course of drying, which, in turn, give rise to considerable deformation and discoloration of ginseng. When the dried ginseng as dehydrated in the above ways are dipped in aqueous ethanol for the purpose of aesthetical appreciation, therefore, they do not restore completely to the original miscellaneous shape and color tone characteristic of and inherent to the untreated crude ginseng and hence have far less value in the view-point of aesthetic appreciation. Further, it is difficult for the dipping aqueous ethanol to permeate into the dried ginseng due to their shrivelled and hardened tissue structure disadvantageously to the extent that it will take at least three months before the aqueous ethanol in which the dried ginseng has been dipped becomes suitable for liquor drug or medicinal beverage. Thus, the pharamacologically active ingredients in the ginseng can only be very slowly extracted into the aqueous ethanol from the previously known dried ginsengs.
Japanese Patent Publication No. 30567/77 describes a method for preparation of a dried ginseng according to the lyophilization (freeze-drying) technique. The prior method of this Japanese Patent comprises forming appropriate numbers of elongate apertures lengthwise within the main trunk of crude ginseng substantially along the central axis of said trunk root and then lyophilizing the pierced root in vacuum. The elongate apertures formed enable fairly rapid drying to proceed to the central part of the ginseng, and the dried ginseng so obtained rather retains the original shape and color tone of the crude ginseng than those of the usual dried products of Ginseng Radix alba and rubra as already noted. The above method according to the lyophilization technique has another advantage that ice crystals develop within the root tissue upon the freezing and can subsequently sublime during the lyophilization to leave many cavities or pores therein, which facilitate smooth permeation of the dipping aqueous ethanol into the dried ginseng and thus rapid extraction of the active ingredients therefrom, to make the ethanolic extract solution suitable for medicinal beverage soon, eg. in about one week.
According to the above method, however, the elongate apertures should be formed by inserting or piercing fine needles at proper places near the crotches of branched small roots extending from the trunk root, upwardly to the central part of the trunk root in such a manner that the aesthetically appreciable appearance of the ginseng product would not be damaged by exposure of the apertures as formed. Since one crude ginseng is extremely different in its shape from another, the proper sites in crude ginseng at which the needle-piercing is to be made vary from one to another. Thus, the work of needle-piercing is impossible to be done mechanically, and it is necessary to check visually and preliminarily decide the proper sites with every ginseng, before carrying out the piercing operation.
Therefore, the work of needle-piercing needs inefficient hand-operation. Moreover, while the dried ginseng obtained by the above-mentioned method has not changed greatly in the shape and color tone, it has been reduced greatly in the size to the degree that the main root trunk diameter is decreased by 17 to 38% as compared to the initial diameter of the raw root trunk. This is because inevitable shriveling took place during the drying step, with lengthwise extending deep wrinkles being formed in the root trunk portion. When the dried ginseng so obtained is dipped in aqueous ethanol, it does not regenerate completely the original shape of crude ginseng, and it looks worse and is far less worthy of being appreciated aesthetically than the orginal crude ginseng.
Further drawback of the method of the aforesaid Japanese Patent occurs due to that crude ginseng has such shape that several branched small roots and fibre-like thin roots are spreading in all directions from the main root trunk portion. Thus, the crude ginseng is too voluminous and hence disadvantageously it can only be frozen and lyophilized with poor efficiency requiring a higher cost for the drying.
We have closely studied these circumstances in an attempt to avoid the above-mentioned drawbacks encountered in the course of the freezing and lyophilization of crude ginseng. As a result, we have now found that a dried ginseng for drugs which fully retains the miscellaneous original shape and color tone inherent to crude ginseng, which permits easy extraction of the pharmacologically active ingredients from the dried product and which is highly worthy of aesthetic appreciation and stands the storage for a long time, can be prepared by a method comprising heating crude ginseng to soften its tissue structure, followed by freezing in an inert gas under pressure and then by lyophilization (freeze-drying).